CN202067514U - Voltage current conversion circuit, data driving circuit, current driving pixel circuit and panel displayer - Google Patents
Voltage current conversion circuit, data driving circuit, current driving pixel circuit and panel displayer Download PDFInfo
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- CN202067514U CN202067514U CN2011201850325U CN201120185032U CN202067514U CN 202067514 U CN202067514 U CN 202067514U CN 2011201850325 U CN2011201850325 U CN 2011201850325U CN 201120185032 U CN201120185032 U CN 201120185032U CN 202067514 U CN202067514 U CN 202067514U
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Abstract
The utility model provides a voltage current conversion circuit, which comprises a data voltage input unit, a threshold voltage compensation unit and a data current output unit. The data voltage input unit is used for receiving data voltage signals, transmitting the data voltage signals to the threshold voltage compensation unit, and transmitting the data voltage signals with threshold voltage of a transistor compensated by the threshold voltage compensation unit simultaneously to the data current output unit. The threshold voltage compensation unit is used for performing threshold voltage compensation of the resistor for the data voltage signals. The data current output unit is used for converting the data voltage signals compensated by the threshold voltage of the resistor into the data current signals to be output. Furthermore, the utility model provides a data driving circuit, a current driving active matrix organic light emitting diode (AMOLED) pixel circuit and a panel displayer.
Description
Technical field
The utility model relates to the flat panel display device technology field, relates in particular to a kind of voltage-current converter circuit, data drive circuit and current drive-type image element circuit and flat-panel monitor.
Background technology
OLED (Organic Light Emitting Diode: Organic Light-Emitting Diode, abbreviation OLED) display of organic electroluminescence is a kind of emerging flat-panel display device, because it has that preparation technology is simple, cost is low, low in energy consumption, luminosity is high, the working temperature wide accommodation, volume is frivolous, response speed is fast, and be easy to realize colored demonstration and large screen display, be easy to realize and driver ic is complementary, is easy to realize advantages such as flexible demonstration, it is had broad application prospects.
The OLED pixel cell is generally in the arranged mode, to constitute image element circuit in the display of organic electroluminescence.Image element circuit is according to the difference of type of drive, can be divided into passive matrix (Passive Matrix Organic Light Emission Display, abbreviation PMOLED) type of drive and active matrix (Active Matrix Organic Light Emission Display is called for short AMOLED) type of drive is two kinds.Though PMOLED type of drive technology is simple, cost is lower, because of there being shortcomings such as cross-talk, high power consumption, low life-span, can not satisfy the needs that high Resolution and Large Size shows.By contrast, the AMOLED type of drive is an all integrated cluster film transistor (Thin Film Transistor is called for short TFT) and memory capacitance in each pixel cell, forms pixel-driving circuit.By drive controlling, realize control, thereby make OLED luminous the electric current that passes through OLED to TFT.Owing to added TFT, make that the OLED in the image element circuit can both be luminous in a controlled frame time, and required drive current is little, low in energy consumption, the life-span is longer, and the large scale that can satisfy the many gray scales of high resolving power shows needs.Simultaneously, AMOLED has remarkable advantages at the aspects such as reduction, power consumption and response time of visible angle, color, is applicable to high information content, high-resolution display.
Simultaneously, AMOLED is a kind of circuit structure of matrix addressing, and its Driving technique is divided into pixel drive technology and peripheral driver technology.The pixel drive technology is utilized pixel-driving circuit that above-mentioned TFT and memory capacitance constitute continuing to light realization condition is provided for OLED; The effect of peripheral drive circuit then is for the active OLED pixel matrix circuit provides correct input signal, and being included as the active OLED picture element matrix provides the sweep signal of gating line by line and provide the data-signal that has display message for each capable OLED pixel cell of gating.Pixel-driving circuit and peripheral drive circuit complement each other, closely cooperate, and finish the operate as normal that drives the AMOLED display screen jointly, are vital contents in the OLED display technique.
As shown in Figure 1, traditional AMOLED pixel-driving circuit is simple two pipe TFT structures, comprises driving transistors T1 and switching transistor T2.Its type of drive can comprise two stages, and promptly data programing stage and data keep the stage.
At data programing in the stage, the capable gating signal V of peripheral drive circuit
SelMake switching transistor T2 conducting, the data voltage V that gating is capable
DataEnter pixel cell through T2, to memory capacitance C
sCharging, along with the grid potential of driving transistors T1 improves gradually, T1 begins conducting, and stabilization sub stage T1 works in the saturation region in programming, and according to the source-drain current formula of TFT saturation region, the output current of T1 promptly by the electric current of OLED is:
I
OLED＝I
T1＝1/2μ
nC
ox(W/L)
T1(V
Data-V
Th)
2............(1)
Wherein, μ
n, C
Ox, W, L, V
ThBe respectively the equivalent carrier mobility of T1, unit-area capacitance, channel width, channel length and the threshold voltage of gate insulation.Can see that the electric current by OLED is subjected to data voltage V
DataControl, thus realize data voltage V
DataProgramming operation to the electric current by OLED.
Keep stage, the capable gating signal V of peripheral drive circuit in data
SelMake switching transistor T2 turn-off, the grid potential of driving transistors T1 is because memory capacitance C at this moment
sIn electric charge existence and remain unchanged, thereby keep lasting driving in the data maintenance stage to OLED.
Though sort circuit is simple in structure, from current expression (that is formula (1)), can see that also electric current not only is subjected to data voltage V by OLED
DataControl, simultaneously, also be subjected to TFT threshold voltage V
ThInfluence, be that two traditional pipe TFT structures can not compensate TFT threshold voltage shift (non-crystalline silicon tft) or threshold voltage inconsistent (low temperature polycrystalline silicon TFT), because the TFT of each pixel cell can not possess on all four performance parameter in the whole image element circuit, its result will cause the electric current that flows through OLED in each pixel cell inconsistent, make each pixel cell luminosity inequality, be the entire display screen brightness irregularities, influence display quality.
In order to solve the inconsistent problem of brightness that traditional AMOLED pixel drive mode threshold voltages is brought, various image element circuits and compensation mechanism are suggested, these image element circuits generally are to solve by the number that increases TFT, its difference according to drive signal can be divided into voltage driven type AMOLED image element circuit (Voltage Programmed Pixel Circuit, be called for short VPPC) and current drive-type AMOLED image element circuit (Current Programmed Pixel Circuit is called for short CPPC) two classes.
Voltage driven type AMOLED image element circuit, its image element circuit utilize voltage signal to the image element circuit driving of programming, and utilizing increases extra transistor and realize compensation to threshold voltage.Single voltage driven type pixel cell as shown in Figure 2, its electric current by OLED is:
I
OLED＝1/2μ
nC
ox(W/L)
T1(V
Data-V
DD)
2............(2)
Can see that this voltage driven type AMOLED image element circuit is after transistor is selected, because V
DDBe given supply voltage value, therefore the current value by OLED only is subjected to data voltage V
DataControl, thereby eliminated threshold voltage V
ThTo the influence of the electric current by OLED, promptly eliminated the inconsistent problem of threshold voltage shift or threshold voltage, improved the degree of stability of pixel cell, the also corresponding display quality that improves display.Owing to utilized voltage signal to drive, therefore make the memory capacitance Cs in the AMOLED image element circuit that the very fast speed that discharges and recharges be arranged simultaneously, thereby can satisfy the needs of large tracts of land, high resolving power demonstration.
At present, voltage driven type AMOLED image element circuit is comparative maturity, the peripheral data signal chip for driving (IC) that the special use that is applicable in the voltage driven type AMOLED image element circuit has also been arranged, the data voltage signal that this peripheral data signal chip for driving produces, be the data-signal that has display message that OLED provides in each capable pixel cell of gating, the driving of can programming to the OLED in a plurality of pixel cells in the voltage driven type AMOLED image element circuit, thus realized the driven of AMOLED image element circuit easily.But, this voltage driven type AMOLED image element circuit is in the compensation that realizes the TFT threshold voltage, many control signals and complicated program process have comparatively been introduced, make threshold compensation circuitry have relatively high expectations to AMOLED image element circuit peripheral data signal chip for driving, the domain wiring of AMOLED image element circuit also becomes complicated.In addition, realize valve value compensation even adopt extra transistor, usually also can only compensate the circuit performance that causes because the drive current that threshold voltage difference causes is degenerated and degenerate, and powerless to the influence that brings such as temperature, carrier mobility difference to the OLED luminescence efficiency.
Current drive-type AMOLED image element circuit, its image element circuit utilize current signal to the image element circuit driving of programming.Be illustrated in figure 3 as the more common driving pixel cell of single current at present, it comprises: the first switching transistor SW1, second switch transistor SW2, memory capacitance Cs, the first driving transistors DR1, second driving transistors DR2 and the OLED.Its driving process is summarized as follows:
In the data programing stage, switching transistor SW1, SW2 are by the conducting of row gating signal, and this row gating signal is supplied with sweep trace SEL by drive element of the grid in the peripheral drive circuit.The data current I that the data-driven unit provides in the peripheral drive circuit
DataThrough switching transistor SW2 memory capacitance Cs is charged.Along with the carrying out of charging, the grid potential of driving transistors DR1 improves gradually, and DR1 begins conducting, and data current begins to flow into OLED through DR1.In the stabilization sub stage of data programing, the total data electric current will flow to OLED by driving transistors DR1.
Keep the stage in data, switching transistor SW1, SW2 are turn-offed by the low signal of selecting, and the electric charge on the memory capacitance Cs continues driving transistors DR2 at this moment, make DR2 keep conducting in this stage, and driving OLED is luminous.This moment, the electric current by OLED was:
I
OLED＝κI
Ddata............(3)
Wherein K is by the breadth length ratio decision of driving transistors DR1 and driving transistors DR2.Can see, this current drive-type AMOLED image element circuit, after transistor is selected, the electric current by OLED only with data current I
DataAnd the breadth length ratio K of driving transistors is relevant, and with all irrelevant such as items such as threshold voltage, temperature, carrier mobilities.
Therefore, than voltage driven type AMOLED image element circuit, current drive-type AMOLED image element circuit is not only realized data current I easily
DataTo the control of the electric current by OLED, thereby realize programming requirement easily to the OLED luminosity; Simultaneously can also eliminate threshold voltage V
Th, temperature and carrier mobility μ
nThe influence that difference is brought.And, because OLED is the current mode device, its luminosity is directly proportional with electric current by OLED, can realize the accurate control and the high stability of display screen GTG by the control of electric current, if therefore adopt the current drives mode to control the brightness of OLED more accurately.
But, almost there is not peripheral data signal chip for driving at present at the special use of current drive-type AMOLED pixel circuit design, directly restricted the application of current drive-type AMOLED image element circuit in actual production.
The utility model content
Technical problem to be solved in the utility model is the deficiency that lacks special-purpose peripheral data signal chip for driving at current drive-type image element circuit in the prior art, a kind of voltage-current converter circuit is provided, comprise this voltage-current converter circuit data drive circuit, comprise the current drive-type AMOLED image element circuit and the flat-panel monitor of this data drive circuit.
The technical scheme that solution the utility model technical matters is adopted is a kind of voltage-current converter circuit, and it comprises data voltage input block, threshold voltage compensation unit and data current output unit, wherein:
The data voltage input block, be used to receive data voltage signal, and send this data voltage signal to the threshold voltage compensation unit, will send the data current output unit to through the data voltage signal that the threshold voltage compensation unit carries out the transistor threshold voltage compensation simultaneously;
The threshold voltage compensation unit is used for described data voltage signal is carried out the transistor threshold voltage compensation;
The data current output unit is used for the data voltage signal through the transistor threshold voltage compensation is converted to data current signal and output.
Preferably, described data voltage input block is the common-source common-gate current mirror circuit.
Preferably, described common-source common-gate current mirror circuit comprises the first transistor (M1), transistor seconds (M2), the 3rd transistor (M3) and the 4th transistor (M4), wherein:
The first transistor (M1), its grid links to each other with the input end of input data voltage signal, and source electrode is connected to first potential reference point (B), and drain electrode links to each other with the drain electrode of the 3rd transistor (M3), and wherein, described first potential reference point (B) is ground;
Transistor seconds (M2), its grid links to each other with its drain electrode, and source electrode links to each other with the threshold voltage compensation unit;
The 3rd transistor (M3), its grid links to each other with its drain electrode, and source electrode is connected to the first power supply (V with certain potentials
DD), wherein, the described first power supply (V
DD) be 10-15V;
The 4th transistor (M4), its grid links to each other with the grid of the 3rd transistor (M3), and source electrode is connected to the first power supply (V
DD), drain electrode links to each other with the drain electrode of transistor seconds (M2).
Preferably, described the first transistor (M1), transistor seconds (M2), the 3rd transistor (M3) and the 4th transistor (M4) all are operated in the saturation region; The 3rd transistor (M3) is identical with the breadth length ratio of the 4th transistor (M4); The breadth length ratio of transistor seconds (M2) equals 4 times of breadth length ratio of the first transistor (M1).
Preferably, described threshold voltage compensation unit comprises the 5th transistor (M5), the 6th transistor (M6), the 7th transistor (M7), the 8th transistor (M8) and the 9th transistor (M9), wherein:
The 5th transistor (M5), its grid links to each other with the grid of transistor seconds (M2) in the data voltage input block, and drain electrode links to each other with the drain electrode of the 7th transistor (M7), and source electrode links to each other with the source electrode of the 9th transistor (M9);
The 6th transistor (M6), its grid links to each other with the source electrode of the 5th transistor (M5), and source electrode links to each other with the grid of the 9th transistor (M9), and drain electrode links to each other with the drain electrode of the 8th transistor (M8);
The 7th transistor (M7), its grid links to each other with its drain electrode, and source electrode is connected to the first power supply (V
DD);
The 8th transistor (M8), its grid links to each other with the grid of the 7th transistor (M7), and drain electrode links to each other with the drain electrode of the 6th transistor (M6), and source electrode is connected to the first power supply (V
DD);
The 9th transistor (M9), its grid all is connected to first potential reference point (B) with drain electrode, and source electrode links to each other with the source electrode of transistor seconds (M2).
Preferably, described the 5th transistor (M5), the 6th transistor (M6), the 7th transistor (M7) and the 8th transistor (M8) all are operated in the saturation region; The 7th transistor (M7) is identical with the breadth length ratio of the 8th transistor (M8), and the 5th transistor (M5) is identical with the breadth length ratio of the 6th transistor (M6).
Preferably, described data current output unit comprises the tenth transistor (M10), and its grid links to each other with the drain electrode of transistor seconds (M2), and source electrode is connected to first potential reference point (B), drains to be the output terminal of electric current and voltage modular converter.
Preferably, described transistor is a thin film transistor (TFT).
The utility model also provides a kind of data drive circuit, comprises data voltage generation module and voltage-current converter circuit, wherein:
The data voltage generation module is used to produce data voltage signal, and the data voltage signal that produces is offered voltage-current converter circuit;
Voltage-current converter circuit adopts foregoing voltage-current converter circuit, be used for the data voltage signal that the data voltage generation module produces is converted to the data current signal, its data voltage input block receives the data voltage signal that the data voltage generation module is produced, and its data current output unit is exported the data converted current signal.
Preferably, described data voltage generation module adopts TFT-LCD data voltage drive integrated circult.
In addition, the utility model also provides a kind of current drive-type AMOLED image element circuit, and the data drive circuit of this current drive-type AMOLED image element circuit adopts foregoing data drive circuit.
A kind of flat-panel monitor that comprises above-mentioned current drive-type AMOLED image element circuit.
The beneficial effect that the utility model obtains is, a kind of voltage-current converter circuit is provided, this change-over circuit can compensate the transistor threshold voltage of this circuit inside, thereby can reach the technique effect that heterogeneity or instability to threshold voltage compensate, and will be converted to the output of data current signal through the peripheral data voltage signal of threshold voltage compensation, because this data drive circuit is simple in structure, therefore has very high reliability.
Thereby, the data drive circuit that comprises this voltage-current converter circuit can be with existing peripheral data signal chip for driving (for example, TFT-LCD data voltage chip for driving) data voltage signal that is produced is converted to the required data current signal of AMOLED image element circuit, realizes the driving of current drive-type AMOLED image element circuit.Compare with developing a kind of data drive circuit that is exclusively used in current drive-type AMOLED image element circuit fully again, can greatly save cost of development, enhance productivity.In addition, this type of drive has not only kept the advantage of the high precision GTG control of existing current drive-type AMOLED image element circuit and high stability, threshold voltage compensation, make and are more suitable for current drive-type AMOLED image element circuit and the flat-panel monitor cost reduction that comprises this current drive-type AMOLED image element circuit producing in enormous quantities.
Description of drawings
Fig. 1 is a kind of structural representation of traditional AMOLED pixel cell;
Fig. 2 is a kind of structural representation of voltage driven type AMOLED pixel cell in the prior art;
Fig. 3 is a kind of structural representation of current drive-type AMOLED pixel cell in the prior art;
Fig. 4 is applicable to the topological structure block diagram of the data drive circuit of current drive-type AMOLED image element circuit for the utility model;
Fig. 5 is applicable to the topological structure figure of the data drive circuit of current drive-type AMOLED image element circuit for the utility model;
Fig. 6 is for using the synoptic diagram that data drive circuit shown in Figure 5 drives the single pixel cell in the current drive-type AMOLED image element circuit;
Fig. 7 is for using the synoptic diagram that data drive circuit shown in Figure 5 drives current drive-type AMOLED image element circuit.
Embodiment
For making those skilled in the art understand the technical solution of the utility model better, the utility model voltage-current converter circuit is comprised that the current drive-type AMOLED image element circuit and the flat-panel monitor of this data drive circuit describe in further detail below in conjunction with the drawings and specific embodiments.
Technical conceive of the present utility model is, designing a change-over circuit is used for the data voltage signal that existing peripheral data signal chip for driving produces is converted to the required data current signal of current drive-type AMOLED image element circuit, the data voltage signal of utilizing existing data-signal chip for driving to produce drives the AMOLED image element circuit, and can obtain to drive preferably effect, and then reduce the design cost of current mode AMOLED image element circuit peripheral data signal chip for driving.
In order to achieve this end, the data voltage signal that the utility model utilizes the data voltage chip for driving commonly used of the TFT-LCD in the LCD in the prior art to be produced drives the AMOLED image element circuit, correspondingly designs a change-over circuit data voltage signal that existing TFT-LCD data voltage chip for driving is produced is converted to the required data current signal of current drive-type AMOLED image element circuit.This change-over circuit comprises data voltage input block, threshold voltage compensation unit and data current output unit, because this circuit has been considered valve value compensation, the data voltage signal that makes the data voltage chip for driving be produced can strict be converted to and drive the required data current signal of AMOLED image element circuit, satisfies the peripheral driver requirement of AMOLED image element circuit.
As shown in Figure 4, in the utility model, the data drive circuit that is applied to current drive-type AMOLED image element circuit comprises data voltage generation module and voltage-current converter circuit two large divisions: the data voltage generation module is used to produce data voltage signal V
Data, and with the data voltage signal V that produces
DataOffer voltage-current converter circuit; Voltage-current converter circuit is used for the data voltage signal that the data voltage generation module produces is converted to the data current signal I that is applicable to that current drive-type AMOLED image element circuit is required
Data, and with data converted current signal I
DataOutput to the data input pin of the respective pixel unit in the current drive-type AMOLED image element circuit.
In the utility model, the data voltage that the data voltage generation module is produced can directly be provided by existing TFT-LCD data voltage chip for driving, that is to say that the data voltage generation module can directly be exported the data voltage that is produced by existing TFT-LCD data voltage chip for driving.
As shown in Figure 4, voltage-current converter circuit comprises data voltage input block, threshold voltage compensation unit and three parts of data current output unit: the data voltage input block is used to receive the data voltage signal V that the data voltage generation module is produced
Data, and the data voltage signal V that the data voltage generation module is produced
DataSend the threshold voltage compensation unit to, will carry out the data voltage signal V of transistor threshold voltage compensation through the threshold voltage compensation unit simultaneously
DataSend the data current output unit to; The threshold voltage compensation unit is used for described data voltage signal V
DataCarry out the transistor threshold voltage compensation; The data current output unit is used for the data voltage signal V through the transistor threshold voltage compensation
DataBe converted to the required data current signal I of AMOLED image element circuit
Data, and with data converted current signal I
DataOutput to the data input pin of the respective pixel unit in the AMOLED image element circuit.
Below, to a specific embodiment of the utility model voltage-current converter circuit be described in detail, in this embodiment, the utility model is described as transistorized example described in the utility model with thin film transistor (TFT) (TFT), that is to say, in following examples were described, transistor promptly referred to thin film transistor (TFT).
As shown in Figure 5, among the embodiment of the present utility model, the data voltage input block comprises: the first transistor M1, transistor seconds M2, the 3rd transistor M3 and the 4th transistor M4 are used to receive the data voltage signal V that the data voltage generation module is produced
Data, and the data voltage signal V that the data voltage generation module is produced
DataSend the threshold voltage compensation unit to, will carry out the data voltage signal V of TFT threshold voltage compensation through the threshold voltage compensation unit simultaneously
DataSend the data current output unit to.Wherein, the grid of the first transistor M1 is as the input end of data voltage input block, and its output terminal with the data voltage generation module links to each other, the source electrode of M1 is connected to the first potential reference point B, the drain electrode of M1 links to each other with the drain electrode of M3, and wherein, the first potential reference point B can be ground; The grid of the 3rd transistor M3 links to each other with its drain electrode, and source electrode is connected to the first power supply V with certain potentials
DDThe grid of the 4th transistor M4 links to each other with the grid of M3, and the source electrode of M4 is connected to the first power supply V
DD, the drain electrode of M4 links to each other with the drain electrode of M2; The grid of transistor seconds M2 links to each other with its drain electrode, and the source electrode of M2 links to each other with the threshold voltage compensation unit as the output terminal of data voltage input block.By above annexation as seen, M3 forms cascade with M4 and is connected, and the basic structure symmetry, so M1, M2, M3 and M4 constitute by input data voltage V
DataThe common-source common-gate current mirror structure of control is to finish the input from data voltage.In this data voltage input block, the first transistor M1, transistor seconds M2, the 3rd transistor M3 and the 4th transistor M4 all are operated in the saturation region.It is identical that the 3rd transistor M3 and the breadth length ratio of the 4th transistor M4 are designed to, and the breadth length ratio of the first transistor M1 and transistor seconds M2 is designed to 4 (W/L)
M1=(W/L)
M2Or 4 ((W/L)
M1/ (W/L)
M2)=(W/L)
M4/ (W/L)
M3The specific implementation of breadth length ratio can be finished by the composition technology of actual production.The realization that below relates to the breadth length ratio design is same therewith.
As shown in Figure 5, in the present embodiment, the threshold voltage compensation unit comprises: the 5th transistor M5, the 6th transistor M6, the 7th transistor M7, the 8th transistor M8 and the 9th transistor M9 are used for realizing described data voltage signal V
DataCarry out TFT threshold voltage compensation (comprising the heteropical compensation of threshold voltage shift or threshold voltage).Wherein, the grid of the 5th transistor M5 links to each other with the grid of M2 in the data voltage input block, and the drain electrode of M5 links to each other with the drain electrode of M7, and the source electrode of M5 links to each other with the source electrode of M9; The grid of the 6th transistor M6 links to each other with the source electrode of M5, and the source electrode of M6 connects the grid of M9 (potential reference point B), and the drain electrode of M6 links to each other with the drain electrode of M8; The grid of the 7th transistor M7 links to each other with its drain electrode, and the source electrode of M7 is connected to the first power supply V
DDThe grid of the 8th transistor M8 links to each other with the grid of M7, and the drain electrode of M8 links to each other with the drain electrode of M6, and the source electrode of M8 is connected to the first power supply V
DDThe grid of the 9th transistor M9 links to each other with its drain electrode (all being connected to potential reference point B), and the source electrode of M9 links to each other with the source electrode of M2 in the data voltage input block.In this threshold voltage compensation unit, the 9th transistor M9 guarantees that the 6th transistor M6 is operated in the saturation region, and the 5th transistor M5, the 6th transistor M6, the 7th transistor M7, the 8th transistor M8 all are operated in the saturation region.The breadth length ratio of the 7th transistor M7 and the 8th transistor M8 is designed to identical, and the breadth length ratio of the 5th transistor M5 and the 6th transistor M6 is designed to identical, to realize the compensation to the TFT threshold voltage.
As shown in Figure 5, in the present embodiment, the data current output unit comprises the tenth transistor M10, is used for the data voltage signal V through the TFT threshold voltage compensation
DataBe converted to the required data current signal I of AMOLED image element circuit
Data, and with data converted current signal I
DataOutput to the data input pin of the respective pixel unit in the AMOLED image element circuit.The grid of the tenth transistor M10 links to each other with the drain electrode of transistor seconds M2, the source electrode of M10 is connected to potential reference point B, the drain electrode of M10 is the output terminal of electric current and voltage modular converter, links to each other with the data input pin of AMOLED picture element matrix through the data current line, and data current signal I is provided
Data
In the present embodiment, first power supply is for providing the positive source V of power supply
DD, V
DDScope is 10-15V; And data voltage V
DataWith data current I
DataThe scope that is provided with require to determine according to the driving of OLED image element circuit in concrete the application.
In the present embodiment, the first transistor M1, transistor seconds M2, the 5th transistor M5, the 6th transistor M6, the tenth transistor M10 are N type TFT; The 3rd transistor M3, the 4th transistor M4, the 7th transistor M7, the 8th transistor M8, the 9th transistor M9 are P type TFT.The circuit that above-mentioned TFT forms has been realized the compensation to TFT threshold voltage unevenness.
Here it should be understood that, the transistorized in the present embodiment control utmost point corresponds to the grid of TFT, the first current lead-through utmost point and the second current lead-through utmost point are respectively source/drain and drain/source, promptly the first current lead-through utmost point and the second current lead-through utmost point can reciprocity, that is to say, first current lead-through extremely can be that source electrode also can be drain electrode, and accordingly, second current lead-through extremely can be that to drain also can be source electrode.
It should be understood that equally, in concrete the application, transistor M1-M10 can select N type TFT simultaneously for use in the circuit, also can select P type TFT simultaneously for use, perhaps mix and select N type TFT and P type TFT for use, only need that simultaneously the port polarity of the transistor M1-M10 of selection type is made corresponding change by the port polarity of present embodiment transistor M1-M10 on connecting and get final product.It should be understood that simultaneously; M1-M10 in the present embodiment also is not limited to TFT; the transistor with voltage control capability that has same process in any employing and the image element circuit is so that the utility model all should be included in the protection domain of the present utility model according to the circuit of above-mentioned working method work; those skilled in the art can change according to actual needs, and no longer accompanying drawing is given unnecessary details herein.
Fig. 6 is for using the synoptic diagram that data drive circuit shown in Figure 5 drives the single pixel cell in the current drive-type AMOLED image element circuit shown in Figure 3.At this moment, the voltage-current converter circuit utilization shown in Figure 5 making technology identical with picture element matrix is integrated in the periphery of picture element matrix substrate, wherein, single pixel cell comprises in the present embodiment: the first switching transistor SW1, second switch transistor SW2, memory capacitance Cs, the first driving transistors DR1, second driving transistors DR2 and the OLED.Several same pixel cell just constitutes image element circuit by arranged, driving circuit in the image element circuit is controlled the luminous demonstration that can realize the OLED array.
The grid of switching transistor SW1 in the single pixel cell shown in Figure 3 is connected to sweep trace SEL, and the output terminal that source electrode is connected to data drive circuit shown in Figure 5 is data current line I
Data, drain electrode is connected to the drain electrode of driving transistors DR1.The grid of switching transistor SW2 is connected to sweep trace SEL, and the output terminal that source electrode is connected to data drive circuit shown in Figure 5 is data current line I
Data, drain electrode is connected to the grid of driving transistors DR1 and driving transistors DR2.The drain electrode of driving transistors DR1 is connected to the drain electrode of switching transistor SW1, and grid is received the drain electrode of switching transistor SW2, and source electrode is connected to the anode electrode of OLED.The drain electrode of driving transistors DR2 is connected to the first power supply V
DD, grid is connected to the drain electrode of switching transistor SW2, and source electrode is connected to the anode electrode of OLED.The anode electrode of organic electroluminescent LED OLED is connected simultaneously with the source electrode of driving transistors DR1 and the source electrode of driving transistors DR2, and cathode electrode is connected to ground wire grounded.First electrode of memory capacitance Cs is connected to the drain electrode of switching transistor SW2 and the grid of driving transistors DR1 and driving transistors DR2, and second electrode is connected to the first power supply V
DDThe data current I that data drive circuit shown in Figure 5 provides
DataTo memory capacitance Cs charging, for the OLED of gating provides the data-signal that has display message, thereby realized the control of data current through switching transistor SW2, realized programming requirement the OLED luminosity to the electric current by OLED.
The principle of work of data drive circuit in the following content introduction present embodiment:
In the data programing stage, the data voltage V that the data voltage generation module produces
DataBe applied to the grid of the first transistor M1 of data voltage input block, because the 3rd transistor M3 is designed to identical with the breadth length ratio of the 4th transistor M4, and the interconnective M3 duty of grid leak is in the saturation region all the time, and M3 is connected with the M4 cascade, therefore the source electrode of M3 and M4 is identical respectively with grid voltage, electric current by M3 is identical with the electric current that passes through M4, i.e. I
M3=I
M4According to TFT saturation region current formula, can obtain:
I
M1＝I
M3＝1/2(W/L)
M1C
OXμ
n(V
Data-V
Th)
2............(4)
I
M2＝I
M4＝1/2(W/L)
M2C
OXμ
n(V
Out-V
A-V
Th)
2............(5)
Wherein: W, L, C
Ox, u
nBe respectively channel width, channel length, capacitive dielectric layer and the carrier mobility of TFT; V
DataFor offer the input voltage value of electric current and voltage modular converter input end (that is M1 grid) by data voltage generation unit module output terminal; V
ThThreshold voltage for TFT; V
OutBe the output voltage values behind the threshold voltage compensation unit compensation (that is the grid voltage of M10); V
AMagnitude of voltage for potential reference point A in the diagram circuit.
Thereby have: I
M1=I
M2... ... ... ... ... ... ... ... (6)
As mentioned above, make the breadth length ratio of the first transistor M1 and transistor seconds M2 be by design: 4 (W/L)
M1=(W/L)
M2, can obtain:
V
Out＝1/2V
Data+V
A+1/2V
Th....................................(7)
Simultaneously, because that the 5th transistor M5 and the breadth length ratio of the 6th transistor M6 are designed to is identical, i.e. (W/L)
M5=(W/L)
M6The 7th transistor M7 is connected with the 8th transistor M8 cascade, therefore equates with the electric current of M8 by M7, i.e. I
M7=I
M8, can obtain:
I
M7＝I
M5＝1/2(W/L)
M5C
OXμ
n(V
Out-V
A-V
Th)
2........................(8)
I
M8＝I
M6＝1/2(W/L)
M6C
OXμ
n(V
A-V
Th)
2.................................(9)
Thereby have: V
Out=2V
A... ... (10)
Therefore, simultaneous formula (7) and (10) have:
V
Out＝V
Data+V
Th..........................(11)
By formula (11) as can be known, process as the output data electric current of the tenth transistor M10 of data current output unit is:
I
Data＝1/2(W/L)
M10C
OXμn(V
Out-V
Th)
2＝1/2(W/L)
M10C
OXμ
nV
Data 2.........(12)
By formula (12) as can be known, the threshold voltage of TFT is irrelevant in the data current of electric current and voltage modular converter output terminal output and the circuit, after promptly passing through the conversion of M5, M6, M7, M8 in the above-mentioned threshold voltage compensation unit, the heterogeneity or the instable compensation of the inner TFT threshold voltage of this change-over circuit have been realized.
As seen, the voltage-current converter circuit of present embodiment and the data drive circuit that comprises this voltage-current converter circuit can drive the data voltage of existing TFT-LCD data voltage chip for driving and be converted to data current and drive, and realize the peripheral driver to current drive-type AMOLED image element circuit.In addition, because this data drive circuit is simple in structure, therefore has very high reliability.
Fig. 7 is the synoptic diagram of the current drive-type AMOLED image element circuit of application data drive circuit shown in Figure 5, several pixel cells shown in Figure 3 just constitute image element circuit by arranged, driving circuit in the image element circuit are controlled the luminous demonstration that can realize the OLED array.In the figure, TFT-LCD data voltage drive IC is above-mentioned data voltage generation module, itself and voltage-current converter circuit be common to constitute data drive circuit of the present utility model, and the columns of the pixel cell in the number of employed voltage-current converter circuit and the AMOLED picture element matrix equates.All the other ingredients among this figure are conventionally known to one of skill in the art, and therefore the descriptions thereof are omitted here.
Adopt above-mentioned current drive-type AMOLED image element circuit can easily produce reliability height, flat-panel monitor that cost is low.
Present embodiment utilizes existing TFT-LCD data voltage drive integrated circult (TFT-LCD data voltage chip for driving) and is equipped with voltage-current converter circuit, thereby solved the deficiency that does not almost have at present at current drive-type AMOLED image element circuit (current drive-type organic electroluminescence display device and method of manufacturing same) peripheral driver special chip, make and are more suitable for current drive-type AMOLED image element circuit and the flat-panel monitor cost reduction that comprises this current drive-type AMOLED image element circuit producing in enormous quantities.
Here point out, in order to eliminate the influence of threshold voltage more up hill and dale, also need adopt certain technology in the mill, the temperature of substrate during Control work for example makes in each row the equivalent carrier mobility μ of the tenth transistor M10 in the potential circuit change-over circuit
n, gate insulation unit-area capacitance C
OxEquate respectively, inner to eliminate change-over circuit because the inconsistent problem of drive current that the inconsistency of TFT threshold voltage may cause causes driven image element circuit different rows pixel cell.
Here it should be understood that, voltage-current converter circuit in the utility model and the data drive circuit that is applicable to current drive-type AMOLED image element circuit not only can be used for comprising in the AMOLED image element circuit that OLED shown in Figure 3 is arranged on the drive TFT source electrode, can also be applied in the AMOLED image element circuit that OLED is arranged on the drive TFT drain electrode.
Here point out, voltage-current converter circuit in the utility model not only can be used for current drive-type AMOLED image element circuit mentioned in the above description, but also can be applicable to the application that other need be converted to the input data voltage signal required data current signal.That is to say, can be according to the requirement of different application, directly use voltage-current converter circuit of the present utility model or (for example carry out corresponding modify based on voltage-current converter circuit of the present utility model, change the design of transistorized breadth length ratio or utilize other equivalent structures that can produce same effect to replace certain unit in the voltage-current converter circuit of the present utility model), any equivalents of then data voltage signal of input being imported voltage-current converter circuit of the present utility model or voltage-current converter circuit of the present utility model is converted to required data current signal.
In actual applications, the input end of the data voltage input block in the voltage-current converter circuit shown in Figure 5 is linked to each other with the output terminal of pending data voltage signal, and the input end of the data current signal that the output terminal of data current output unit and reception are converted links to each other and gets final product.Because concrete structure is identical with above description, therefore omit its detailed description here.
Be understandable that above embodiment only is the illustrative embodiments that adopts for principle of the present utility model is described, yet the utility model is not limited thereto.For those skilled in the art, under the situation that does not break away from spirit of the present utility model and essence, can make various modification and improvement, these modification and improvement also are considered as protection domain of the present utility model.For example, the data voltage input block in the utility model, threshold voltage compensation unit and data current output unit are not limited to circuit structure shown in Figure 5, also can adopt other similar circuit to realize function described in the utility model.
Claims (12)
1. a voltage-current converter circuit is characterized in that, comprises data voltage input block, threshold voltage compensation unit and data current output unit, wherein:
The data voltage input block, be used to receive data voltage signal, and send this data voltage signal to the threshold voltage compensation unit, will send the data current output unit to through the data voltage signal that the threshold voltage compensation unit carries out the transistor threshold voltage compensation simultaneously;
The threshold voltage compensation unit is used for described data voltage signal is carried out the transistor threshold voltage compensation;
The data current output unit is used for the data voltage signal through the transistor threshold voltage compensation is converted to data current signal and output.
2. voltage-current converter circuit according to claim 1 is characterized in that, described data voltage input block is the common-source common-gate current mirror circuit.
3. voltage-current converter circuit according to claim 2 is characterized in that, described common-source common-gate current mirror circuit comprises the first transistor (M1), transistor seconds (M2), the 3rd transistor (M3) and the 4th transistor (M4), wherein:
The first transistor (M1), its grid links to each other with the input end of input data voltage signal, and source electrode is connected to first potential reference point (B), and drain electrode links to each other with the drain electrode of the 3rd transistor (M3), and wherein, described first potential reference point (B) is ground;
Transistor seconds (M2), its grid links to each other with its drain electrode, and source electrode links to each other with the threshold voltage compensation unit;
The 3rd transistor (M3), its grid links to each other with its drain electrode, and source electrode is connected to the first power supply (V with certain potentials
DD), wherein, the described first power supply (V
DD) be 10-15V;
The 4th transistor (M4), its grid links to each other with the grid of the 3rd transistor (M3), and source electrode is connected to the first power supply (V
DD), drain electrode links to each other with the drain electrode of transistor seconds (M2).
4. voltage-current converter circuit according to claim 3 is characterized in that, described the first transistor (M1), transistor seconds (M2), the 3rd transistor (M3) and the 4th transistor (M4) all are operated in the saturation region; The 3rd transistor (M3) is identical with the breadth length ratio of the 4th transistor (M4); The breadth length ratio of transistor seconds (M2) equals 4 times of breadth length ratio of the first transistor (M1).
5. voltage-current converter circuit according to claim 3, it is characterized in that, described threshold voltage compensation unit comprises the 5th transistor (M5), the 6th transistor (M6), the 7th transistor (M7), the 8th transistor (M8) and the 9th transistor (M9), wherein:
The 5th transistor (M5), its grid links to each other with the grid of transistor seconds (M2) in the data voltage input block, and drain electrode links to each other with the drain electrode of the 7th transistor (M7), and source electrode links to each other with the source electrode of the 9th transistor (M9);
The 6th transistor (M6), its grid links to each other with the source electrode of the 5th transistor (M5), and source electrode links to each other with the grid of the 9th transistor (M9), and drain electrode links to each other with the drain electrode of the 8th transistor (M8);
The 7th transistor (M7), its grid links to each other with its drain electrode, and source electrode is connected to the first power supply (V
DD);
The 8th transistor (M8), its grid links to each other with the grid of the 7th transistor (M7), and drain electrode links to each other with the drain electrode of the 6th transistor (M6), and source electrode is connected to the first power supply (V
DD);
The 9th transistor (M9), its grid all is connected to first potential reference point (B) with drain electrode, and source electrode links to each other with the source electrode of transistor seconds (M2).
6. voltage-current converter circuit according to claim 5 is characterized in that, described the 5th transistor (M5), the 6th transistor (M6), the 7th transistor (M7) and the 8th transistor (M8) all are operated in the saturation region; The 7th transistor (M7) is identical with the breadth length ratio of the 8th transistor (M8); The 5th transistor (M5) is identical with the breadth length ratio of the 6th transistor (M6).
7. voltage-current converter circuit according to claim 5, it is characterized in that, described data current output unit comprises the tenth transistor (M10), its grid links to each other with the drain electrode of transistor seconds (M2), source electrode is connected to first potential reference point (B), drains to be the output terminal of electric current and voltage modular converter.
8. according to each described voltage-current converter circuit of claim 3～7, it is characterized in that described transistor is a thin film transistor (TFT).
9. a data drive circuit comprises data voltage generation module and voltage-current converter circuit, wherein:
The data voltage generation module is used to produce data voltage signal, and the data voltage signal that produces is offered voltage-current converter circuit;
Voltage-current converter circuit adopts each described voltage-current converter circuit of claim 1～8, be used for the data voltage signal that the data voltage generation module produces is converted to the data current signal, the data voltage signal that its data voltage input block input data voltage generation module is produced, its data current output unit is exported the data converted current signal.
10. data drive circuit according to claim 9 is characterized in that, described data voltage generation module adopts TFT-LCD data voltage drive integrated circult.
11. a current drive-type AMOLED image element circuit comprises data drive circuit, it is characterized in that, described data drive circuit adopts claim 9 or 10 described data drive circuits.
12. a flat-panel monitor comprises image element circuit, it is characterized in that, described image element circuit adopts the described current drive-type AMOLED of claim 11 image element circuit.
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